. Bought new chain 90sg-56. Chain does not fit

First, stop your engine. Check to make sure that the chain brake isn't engaged. The chain brake can activate automatically by a sudden movement or impact. You can disengage the chain brake by pulling the chain brake hand guard back against the front handle and releasing slowly. If the chain brake is disengaged and the chain does not turn; turn off the saw, then check the drive links on the chain, the bar groove and the sprocket nose on the bar. A burr on the drive links will bind the chain in the bar. If the bar has been pinched, the chain will not pass freely through the groove. If a sliver of wood has gotten into the sprocket nose, it will not turn at all. Also, look at the drive sprocket on the saw itself to see if it has a groove worn into it. A drive sprocket with a groove worn into it will damage the chain.

Check that the chain brake is in disengaged position by
moving the front hand guard towards the front handle.
Remove the bar nuts and remove the clutch cover (chain
brake). Take off the transportation ring.
Fit the bar over the bar bolts. Place the bar in its rearmost
position. Place the chain over the drive sprocket locate it in
the groove on the bar. Begin on the top edge of the bar.

Make sure that the edges of the cutting links are facing
forward on the top edge of the bar.
Fit the clutch cover (chain brake) and locate the chain
adjuster pin in the cut-out in the bar. Check that the drive
links of the chain fit correctly on the drive sprocket and that
the chain is in the groove on the bar. Tighten the bar nuts
finger-tight.
Tension the chain by turning the chain tensioning screw
clockwise using the combination spanner. The chain
should be tensioned until it does not sag from the
underside of the bar.
The chain is correctly tensioned when it does not sag from
the underside of the bar, but can still be turned easily by
hand. Hold up the bar tip and tighten the bar nuts with the
combination spanner.
When fitting a new chain, the chain tension has to be
checked frequently until the chain is run-in. Check the
chain tension regularly. A correctly tensioned chain
ensures good cutting performance and long life.

If the brake has been entirely removed, then check the lubrication and tension of the chain--you should be able to turn the chain by hand fairly easily. If it looks dry with little or no oil, remove the bar and chain. Clean the side of the engine case where the bar fits to, then start the engine. Oil should ooze out of the side port. If nothing, then the oil pump, oil line, or filter in the tank may need service. If ok, then clean the bar drive-end oil passages--especially the two small holes that feed oil from the large holes out to the chain groove on each edge. When back together, run the bar tip at speed near some cardboard for a couple of moments--it should throw off a thin line of oil. There should be a volume adjustment screw head under the case near the chain return area--turn it CW to decrease volume. Hope this helps!

Release the chain brake. Remove the nuts/bolts that hold the right hand cover over the drive end of the bar. With the cover off, the bar will slide back toward the engine and allow the chain to be removed. Note the direction of the cutting teeth! Clean the side of the engine where the bar fits to, and the small oil passages in the bar drive end that run from the large holes out to the chain groove on each edge. Also clean the entire chain groove. Fit the new chain to the sprocket, then insert the bar and work the chain onto it. Pull out on the bar until the chain fits fairly tight, then fit the cleaned cover over the drive. You may have to change the position of the chain adjustment screw a few turns to allow the adjustment 'tang' to drop into one of the large holes in the bar. Make sure the cover is fully seated, then run the fasteners down finger tight. Turn the chain adjuster screw CW until the chain pulls up to the bottom edge of the bar, but not so tight that you can't turn the chain by hand. Tighten the fasteners fully and recheck chain tension. Start the engine and run the tip of the bar near some cardboard at speed for a moment or two--proper oiling is indicated by a thin line of oil thrown onto the cardboard. Be sure to keep the chain teeth sharp and properly adjust chain tension--don't allow it to droop when cutting. Hope this helps!

Make sure the bar and chain is being properly lubricated by running the saw at speed with the tip near some cardboard--it should throw off a thin line of oil after a moment or two. If dry, remove the bar and chain (make sure the chain brake is set to off), and clean the engine area where the bar fits to it. Start the engine--oil should ooze out of the small port in the engine side. If ok, clean the small oil passages that run from the large holes (in the drive end of the bar) out to the chain groove on the bar edge. Wash out the interior of the clutch hub with spray carburetor cleaner to remove excess oil. Reassemble the bar/chain and adjust the chain until it just comes up to the lower bar, but not so tight that you can't turn the chain easily by hand. Make sure the chain is filed sharp enough to cut your fingers if not careful. Hope this helps!

Remove the bar and chain after releasing the chain brake. Clean the cover and the area where the bar fits to the engine. Start the engine and watch for oil oozing out of the side port where the bar fits. If ok, clean the bar end oil passages including the two small channels that go from the large holes out to the chain groove on each side. Clean the entire groove and check the tip sprocket if equipped. If no oil came out of the port, then you need to inspect the oil pump, lines, and tank filter for plugging or damage. When oil comes out as specified, insert the bar, push back, and fit the chain over the sprocket then work it over the bar. Make sure the teeth cut toward you on the bottom run. Pull the bar out to tighten the chain, then back off the chain adjustment screw several turns. Fit the cover, making sure the adjustment tang fits into one of the large holes in the bar, the run the fasteners down finger tight. Adjust the screw till the chain pulls up to the bar, but allows the chain to be moved by hand. Tighten the mountings and recheck the tension. Run the saw tip near a piece of cardboard at speed for a few moments--it should throw off a thin line of oil onto the cardboard. Make sure the chain is properly sharpened. Hope this helps!

Remove the drive end side cover after releasing the chain brake if it exists and removing the mounting nuts. The bar should slide back and allow the old chain to be removed. Take out the bar and clean it's oil passages including the two small channels that go out to the chain groove. Clean the entire chain groove. Clean the motor case side where the bar fits to. Run the motor for a few moments to see if oil oozes out of the side port. If ok, reinstall the bar and push back. Thread the new chain over the sprocket, then work it over the bar making sure the bottom run of chain cuts toward you. Pull the bar outward. Replace the cleaned cover making sure the adjustment tang drops into one of the large holes in the bar--you may have to back out the adjustment screw several turns. Replace the mounting nuts finger tight and adjust the chain until it pulls the lower run of chain up to the bar, yet you can still pull the chain by hand. Tighten the bar nuts firmly and recheck the chain tension. Check for proper oiling by running the saw tip near cardboard for several moments--it should leave a thin line of oil on the cardboard. Hope this helps!

Release the chain brake. Back off the chain adjustment screw several turns and remove the two large cover nuts. Remove the drive cover, then pull the bar back toward you. This will allow the old chain to be removed. Remove the bar and clean the entire area where the bar mounted. Check the outside edges of the chain groove area for any flaring out of the bar metal due to wear. Use a flat file to cut off this flaring edge (at about 45 degrees) so that nothing projects beyond the bar vertical surface on both sides. Turn the bar upside down to even the wear in the chain groove. Clean the oil holes in the bar end including the small channels that bring oil from large holes out to the chain groove on each side and clean the entire chain groove. Insert the bar, then feed the new chain with the teeth on the lower run cutting toward you, onto the sprocket, then work it over the entire bar and pull the bar out as far as it will go. Install the cover (which has been cleaned too) and run the nuts on finger tight (make sure the adjustment tang dropped into a large hole at the bar rear). Turn the adjustment screw CW until the chain ceases to droop from the lower bar, but the chain can still be pulled by hand. Tighten the large nuts firmly and recheck chain tension--if ok, start the engine and hold the bar tip near a piece of cardboard while the engine runs at speed for several moments--you should get a thin line of oil thrown off onto the cardboard. Hope this helps!

Make sure the chain brake is off (pull it toward you), then remove the bar mounting nut(s)/bolt(s) and the remove the side cover, bar, and chain. Clean the oil passages in the rear of the bar including two small passages that run from the larger holes out to the chain groove on each side. Clean the entire chain groove and make sure the end sprocket turns freely and is well oiled. Clean the engine face where the bar fits, then start the engine. Oil should ooze out of a small port in the engine case. If ok, then lay out the chain so that it can be inspected for bent links, dry/sticking joints, or missing/badly worn drive teeth. Inspect the sprocket on the clutch outer drum component for wear or damaged teeth. Make sure the pitch of the chain teeth match those of the drive sprocket (is this a new chain?). Check the hub bearing of the clutch drum for obvious wear. If all looks good, fit the chain around the clutch sprocket, then slip the bar into the the engine mounting space and work the chain over the entire bar. When setting the outer cover, make sure the adjuster tang fits into the related bar hole, then attach the clamp nut(s)/bolt(s), run up finger tight. Use the adjuster to set the chain tension--it should just pull the lower part of the chain up to the bar plus a little more. Check that you can move the chain by hand without any binding, then tighten the clamp bolts/nuts firmly. Recheck that the chain is properly tensioned. If not, re-loosen the clamp fasteners and re-tension the chain. When the clamp fasteners are tight, the tension must be rechecked. Hope this long-winded response helps!

When you remove the chain-drive side cover, bar and chain, you will find a small port in the side of the engine case where the bar fits to it. Clean the area well, and start the engine. It should ooze out oil from this port after a moment or two of running. Clean the holes and bar groove of sawdust--especially the two small holes that pass from the large oil holes out to the chain groove on each side of the drive end of the bar. Reinstall the chain (teeth cut toward you on the bottom run) and bar (turn it over from time to time to equalize the wear on the bar), then fit the cover over the bar--it helps to back off the adjustment screw several turns to ease re-assembly. Make sure the chain brake is released when doing this. With the mounting nut(s) finger tight, tighten the adjustment screw until the chain doesn't droop from the lower side of the bar, yet allows the chain to be turned by hand. Check the chain oiling by running the bar tip near a piece of cardboard--it should throw off a thin line of oil after several moments of running at speed. Hope this helps!